Onion flavour composition and method for the preparation thereof

ABSTRACT

The invention relates to a method of producing an onion flavour composition, said method comprising:providing onion component selected from fresh onion, dehydrated onion and combinations thereof;providing onion juice concentrate having a dry matter content of 40-95 wt. %;mixing the onion component with the onion juice concentrate in a weight ratio, calculated on a dry matter basis, of 100 parts by weight of dry matter from onion component with 60 to 1000 parts by weight of dry matter from onion juice concentrate, to produce an onion mix;subjecting the onion mix to a heat treatment at a temperature of more than 100° C. for at least 5 minutes; anddrying the onion mix to a water content of less than 10 wt. % simultaneous with and/or after the heat treatment.This method yields a shelf-stable onion flavour composition that has an intense flavour, and that can suitably be used to impart the flavour of sautéed onion to a wide variety of edible products.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of producing an onion flavourcomposition, said method comprising:

-   -   providing onion component selected from fresh onion, dehydrated        onion and combinations thereof;    -   providing onion juice concentrate;    -   mixing the onion component with the onion juice concentrate to        produce an onion mix;    -   subjecting the onion mix to a heat treatment at a temperature of        more than 100° C.; and    -   drying the onion mix to a water content of less than 10 wt. %        simultaneous with and/or after the heat treatment.

The onion flavour composition so obtained can suitably be incorporatedin edible products to impart the flavour of sautéed onion.

BACKGROUND OF THE INVENTION

The onion (Allium cepa L.), is a vegetable that is the most widelycultivated species of the genus Allium. Its close relatives include thegarlic, leek, chive, and Chinese onion.

Onions are commonly chopped and used as an ingredient in various heartywarm dishes, and may also be used as a main ingredient in their ownright, for example in French onion soup, creamed onions, and onionchutney. Onions are versatile and can be baked, boiled, braised,grilled, fried, roasted, sautéed, or eaten raw in salads.

Onions are available in fresh, frozen, canned, caramelised, pickled, andchopped forms. The dehydrated product is available as kibbled, sliced,ring, minced, chopped, granulated, and powder forms.

Onion powder is a seasoning widely used when the fresh ingredient is notavailable. It is made from finely ground, dehydrated onions. Beingdehydrated, it has a long shelf life. However, the flavour intensity ofonion powder is rather low and its flavour profile is quite differentfrom the onion flavour profile that is desired in various foodapplications, e.g. the flavour of sautéed onions.

U.S. 2002/0155193 describes a method for preparing an onion/garlicbiohydrolysate based

-   -   flavouring base which comprises:    -   mixing water with onion, garlic, or onion and garlic to form a        mixture;    -   hydrolysing the mixture with one or more technical enzymes; and    -   thermally treating the hydrolysate at a temperature and for a        time sufficient for providing a flavouring base.

U.S. 2012/0114827 describes a process for producing an onion extract,the process comprising: any one of the following steps (a) to (d); and astep of distribution washing a crude onion extract, onion suspension orconcentrate thereof, which has been obtained by the following step, withan organic solvent,

-   -   (a) a step of heating the crude onion extract or concentrate        thereof, which is obtained by at least either extracting or        squeezing a fresh onion;    -   (b) a step of heating a fresh onion, and then obtaining the        crude onion extract or concentrate thereof by at least either        extracting or squeezing;    -   (c) a step of heat-extracting a fresh onion, thereby giving the        crude onion extract or concentrate thereof; and    -   (d) a step of heating a fresh onion and then cutting into small        pieces, thereby giving the onion suspension or concentrate        thereof.

KR 2018 0005938 describes a method of manufacturing a highlyconcentrated onion juice, comprising:

(a) washing an onion;

(b) heating the onion;

(c) filtering the heated onion to separate onion juice and onion solids;

(d) reheating the onion juice;

(e) drying the onion solids;

(f) pulverizing the dried onion solids;

(g) heating and re-heating the reheated onion juice in the vacuumconcentrator after the step (d);

(h) adding the onion solid powder pulverized in the step (f) to theconcentrated onion concentrate of step (g);

dispersing the pulverized onion solid powder with a stirrer, and thenpost-heating at 80 to 95° C. for 10 to 25 minutes;

transferring the pellets to a packaging machine, and filling the pelletswith the packaging paper.

CN 102 273 606 describes a method for preparing an onion powder, saidmethod comprising the following steps:

-   -   grind onions, followed by the addition of cellulase and        enzymolysis in 0.5-3 hours to obtain an enzymolysed onion        solution;    -   add onion powder, concentrated onion juice, spice powder, edible        oil and water, and heat to 120-130° C. under stirring for 1-5        hours;    -   cool to 50-70° C., add butylhydroxy-anisole, xanthan gum,        maltodextrin, pass through a colloid mill and homogenize at        20-30 MPa pressure;    -   spray dry the homogenized mixture.

EP-B 2 485 604 describes a process to produce a concentrated vegetableflavour comprising,

-   -   preparing a composition comprising a vegetable, an oil and a        yeast extract and/or yeast autolysate,    -   intimately mixing the composition in an extruder at a        temperature between 100° C. and 160° C. and a reaction time        between 1 second and 1 week, sufficient for the concentrated        vegetable flavour to develop, wherein the water content of the        composition before or during step b) is between 1% and 8% w/w        based on the total weight of the composition

EP-B 2 801 264 describes a method for producing a salty taste enhancer,comprising heating liquid of a mashed liliaceae vegetable, juice of aliliaceae vegetable, enzyme-treated liquid of a liliaceae vegetable, ora concentrate thereof. The Examples of describe the preparation of asalty taste enhancer by combining concentrated onion juice with finelyground plant tissue from onion, followed by heating.

SUMMARY OF THE INVENTION

The inventors have developed a method of producing a shelf-stable onionflavour composition that has an intense flavour, and that can suitablybe used to impart the flavour of sautéed onion to a wide variety ofedible products. The method comprises the following steps:

-   -   providing onion component selected from fresh onion, dehydrated        onion and combinations thereof;    -   providing onion juice concentrate having a dry matter content of        40-95 wt. %;    -   mixing the onion component with the onion juice concentrate in a        weight ratio, calculated on a dry matter basis, of 100 parts by        weight of dry matter from onion component with 60 to 1000 parts        by weight of dry matter from onion juice concentrate, to produce        an onion mix;    -   subjecting the onion mix to a heat treatment at a temperature of        more than 100° C. for at least 5 minutes; and    -   drying the onion mix to a water content of less than 10 wt. %        simultaneous with and/or after the heat treatment.

The invention also relates to an onion flavour composition that isobtained by the aforementioned method, said onion flavour compositioncomprising:

-   -   at least 2.5 mg/kg of group A substances selected from dimethyl        trisulfide, dimethyl tetrasulfide, dipropyl disulfide,        2-methyl-2-pentenal and 3,4-dimethylthiophene and combinations        thereof;    -   0-4 mg/kg of group B substances selected from furfural,        isobutyraldehyde, 5-methylfurfural, cis-methyl-1-propenyl        disulphide and combinations thereof; wherein the group A        substances and the group B substances are present in the onion        flavour composition in a molar ratio of at least 1:1.

The invention further relates to the use of this onion flavourcomposition in edible products.

DETAILED DESCRIPTION OF THE INVENTION

A first aspect of the invention relates to a method of producing anonion flavour composition, said method comprising:

-   -   providing onion component selected from fresh onion, dehydrated        onion and combinations thereof;    -   providing onion juice concentrate having a dry matter content of        40-95 wt. %;    -   mixing the onion component with the onion juice concentrate in a        weight ratio, calculated on a dry matter basis, of 100 parts by        weight of dry matter from onion component with 60 to 1000 parts        by weight of dry matter from onion juice concentrate, produce an        onion mix;    -   subjecting the onion mix to a heat treatment at a temperature of        more than 100° C. for at least 5 minutes; and    -   drying the onion mix to a water content of less than 10 wt. %        simultaneous with and/or after the heat treatment.

The term “onion” as used herein, unless indicated otherwise, refers toonion bulb.

The term “fresh onion” as used herein refers to non-dehydrated wholeonion or to non-dehydrated pieces of onion.

The term “dehydrated onion” as used herein refers to the materialobtained after dehydrating fresh onion, especially after dehydratingchopped or pureed fresh onion.

The term “onion powder” as used herein refers to dehydrated onion in theform of a powder consisting of particles of dried onion.

The term “onion juice” as used herein refers to the liquid that isobtained by pressing onions.

The term “onion juice concentrate” as used herein refers to onion juicefrom which at least a part of the water has been removed, e.g. byevaporation or reverse osmosis.

The term “onion pomace” as used herein refers to the solid residue thatremains after pressing onions for juice. The term “onion pomace” alsoencompasses dried onion pomace.

The water content of the onion flavour composition or of ingredientsused in the preparation of the onion flavour composition can suitably bedetermined by means of Karl Fischer Titration.

The dry matter content of the onion flavour composition and ofingredients used in the preparation of the onion flavour compositionequals 100 wt. % minus the water content (in wt. %).

The onion component employed in the present method preferably ispreferably selected from fresh onion, onion powder and combinationsthereof. Most preferably, the onion component is fresh onion. The freshonion that is employed in the present method typically contains 60-88wt. % water. More preferably, the fresh onion has a water content of70-85 wt. %.

The onion juice concentrate that is employed in the present methodpreferably has a dry matter content of 50-90 wt. %, more preferably of60-88 wt. % and most preferably of 70-85 wt. %.

The onion mix that is obtained by mixing the onion component with theonion juice concentrate, typically is a suspension of pieces of onion.Such a suspension may be prepared by mixing chopped fresh onion with theonion juice concentrate. Alternatively, the suspension may be preparedby combining fresh onion with the onion juice concentrate, followed by aprocessing step in which the fresh onion is cut into pieces anddispersed throughout the onion juice concentrate.

The onion mix that is obtained by the mixing of the onion component withonion juice concentrate preferably has a dry matter content of 20-80 wt.%, more preferably a dry matter content of 30-70 wt. % and mostpreferably a dry matter content of 35-60 wt. %.

The combination of onion component and onion juice concentrate typicallyconstitutes at least 50 wt. %, more preferably at least 80 wt. %, mostpreferably at least 95 wt. % of the onion mix.

In a preferred embodiment, the onion mix is prepared by mixing the onioncomponent with the onion juice concentrate in a weight ratio, calculatedon a dry matter basis, of 100 parts by weight of dry matter from onioncomponent with 100 to 800 parts by weight of dry matter from onion juiceconcentrate, more preferably by mixing the onion component with theonion juice concentrate in a weight ratio, calculated on a dry matterbasis, of 100 parts by weight of dry matter from onion component with120 to 600 parts by weight of dry matter from onion juice concentrate.

In the present method, the onion mix is preferably subjected to a heattreatment at a temperature of 110-200° C., more preferably at atemperature of 120-170° C. The duration of the heat treatment preferablyis in the range of 8 to 600 minutes, more preferably in the range of10-300 minutes.

The onion mix may be dried using different drying techniques.Preferably, the onion mix is dried by means of belt drying, tray drying,drum drying or spray drying. More preferably, the onion mix is dried bybelt drying or tray drying. Most preferably, the onion mix is dried bymeans of belt drying.

Preferably, the onion mix is dried at a reduced pressure of not morethan 100 mbar, more preferably at a reduced pressure of less than 50mbar, most preferably at a reduced pressure of 0.5-20 mbar.

According to a particularly preferred embodiment, the heat treatment ofthe onion mix and the drying of the onion mix to a water content of lessthan 10 wt. % are carried out simultaneously. Accordingly, the onion mixis preferably dried at a temperature of more than 100° C. for at least10 minutes. More preferably, the onion mix is dried at a temperature of110-200° C., most preferably at a temperature of 120-170° C. Theduration of the drying is preferably in the range of 8 to 200 minutes,more preferably in the range of 10-120 minutes dried for 20 to 600minutes at a temperature of 110-200° C., more preferably at atemperature of 120-170° C.

Typically, the onion mix is dried to a water content of less than 8 wt.%, more preferably of less than 5 wt. %.

In a particularly preferred embodiment, the onion mix is mixed withonion pomace before or after the drying of the onion mix. Mostpreferably, the onion mix is mixed with onion pomace after the heattreatment and the drying of the onion mix.

In accordance with one preferred embodiment, the dried onion mix ismixed with onion pomace in a weight ratio, calculated on a dry matterbasis, of 100 parts by weight of dry matter from dried onion mix with 3to 80 parts by weight of dry matter from onion pomace, said onion pomacehaving a dry matter content of 20-100 wt %. More preferably, the driedonion mix is mixed with onion pomace in a weight ratio, calculated on adry matter basis, of 100 parts by weight of dry matter from dried onionmix with 4 to 60 parts by weight of dry matter from onion pomace. Mostpreferably, the dried onion mix is mixed with onion pomace in a weightratio, calculated on a dry matter basis, of 100 parts by weight of drymatter from dried onion mix with 8 to 40 parts by weight of dry matterfrom onion pomace.

The onion pomace employed in the present method present methodpreferably is dried onion pomace. According to a particularly preferredembodiment, the onion pomace has been dried at a temperature of at least100° C. for at least 20 minutes. More preferably, the onion pomace hasbeen dried at a temperature of 105-180° C., most preferably at atemperature of 110-150° C. The drying period preferably lies in therange of 40-800 minutes, most preferably in the range of 60-600 minutes.

The dried onion pomace that is employed in the present processpreferably has been dried by means of hot air drying.

Preferably, the onion pomace that is mixed with the dried onion mix hasa dry matter content of 70-100 wt. %, more preferably of 90-100 wt. %and most preferably of 95-100 wt. %.

The present method preferably comprises the step of milling the driedonion mix or the mixture of dried onion mix and onion pomace.Preferably, the milled onion flavour composition so obtained is a powderhaving a mass weighted mean diameter of less than 1 mm, more preferablyhaving a mass weighted mean diameter in the range of 0.1-0.8 mm.

Another aspect of the present invention relates to an onion flavourcomposition that is obtained by the production method that is describedherein, said onion flavour composition comprising:

-   -   at least 2 at least 2.5 mg/kg of group A substances selected        from dimethyl trisulfide, dimethyl tetrasulfide, dipropyl        disulfide, 2-methyl-2-pentenal and 3,4-dimethylthiophene and        combinations thereof;    -   0-4 mg/kg of group B substances selected from furfural,        isobutyraldehyde, 5-methylfurfural, cis-methyl-1-propenyl        disulphide and combinations thereof;

wherein the group A substances and the group B substances are present inthe onion flavour composition in a molar ratio of at least 1:1.

In accordance with a particularly preferred embodiment, the bulk of thedry matter contained in the onion flavour composition is derived fromonion. Accordingly, dry matter from onion preferably constitutes atleast 90 wt. %, more preferably at least 95 wt. % and most preferably atleast 98 wt. % of the dry matter contained in the onion flavourcomposition.

The onion flavour composition of the present invention preferably is apowder, more preferably a powder having a mass weighted mean diameter ofless than 1 mm, most preferably having a mass weighted mean diameter inthe range of 0.1-0.8 mm.

The onion flavour composition typically contains at least 2.8 mg/kg andmost preferably 3-20 mg/kg of group A substances selected from dimethyltrisulfide, dimethyl tetrasulfide, dipropyl disulfide,2-methyl-2-pentenal and 3,4-dimethylthiophene and combinations thereof.The group A substances contribute to the sautéed onion flavour characterof the onion flavour composition.

Preferably, the onion flavour composition contains 0-3 mg/kg, morepreferably 0-2.5 and most preferably 0-2 mg/kg of group B substancesselected from furfural, isobutyraldehyde, 5-methylfurfural,cis-methyl-1-propenyl disulphide and combinations thereof.

The aforementioned group A substances and group B substances aretypically present in the onion flavour composition in a molar ratio ofat least 2:1, more preferably of at least 3:1, and most preferably of atleast 3.5:1.

In a preferred embodiment, the onion flavour composition contains atleast 2 mg/kg, more preferably at least 3 mg/kg of dimethyl trisulfide,3,4-dimethylthiophene and/or 2-methyl-2-pentenal

The combination of 5-methylfurfural and isobutyraldehyde is preferablynot contained in the onion flavour composition or present in a combinedconcentration of not more than 2 mg/kg more preferably of not more than1 mg/kg.

A further aspect of the invention relates to a process of producing anedible product, said process comprising combining the onion flavourcomposition of the present invention with one or more other edibleingredients.

The present process preferably comprises application of the onionflavour composition in an amount sufficient to add at least 10 μg/kg,more preferably 40-800 μg/kg of group A substances selected fromdimethyl trisulfide, dimethyl tetrasulfide, dipropyl disulfide,2-methyl-2-pentenal and 3,4-dimethylthiophene and combinations thereof.

The onion flavour composition is preferably applied in an amount thatconstitutes at least 0.5 wt. %, preferably 0.8-8 wt. % of the edibleproduct.

The present process is particularly suitable for the production of anedible product selected from soups, sauces, bouillons, savouryconcentrates, dressings, seasonings and snacks. The present process isparticularly suitable for the production of edible products in the formdry powders (e.g. dry soups, dry sauces or bouillon powders) or in theform of cubes or granulates (e.g. bouillon cubes or bouillongranulates).

The onion flavour composition of the present invention can suitably beused to enhance/improve the onion flavour of edible products thatcontain onion. Thus, according to a particularly preferred embodiment,the present process comprises combining the onion flavour compositionwith pieces of onion.

Dry matter from onion preferably constitutes at least 1 wt. %, morepreferably 2-20 wt. % of the dry matter contained in the edible product.

Per kg of dry matter from onion the edible product preferably contains:

-   -   at least 2.5 mg of group A substances selected from dimethyl        trisulfide, dimethyl tetrasulfide, dipropyl disulfide,        2-methyl-2-pentenal and 3,4-dimethylthiophene and combinations        thereof;    -   0-10 mg of group B substances selected from furfural,        isobutyraldehyde, 5-methylfurfural, cis-methyl-1-propenyl        disulphide and combinations thereof;

wherein the group A substances and the group B substances are present inthe onion flavour composition in a molar ratio of at least 1:1,preferably of at least 2:1, more preferably of at least 3:1.

The edible product preferably comprises, per kg of dry matter fromonion, at least 3 mg, more preferably at least 3.3 mg, and mostpreferably at least 3.5 mg of the group A substances.

According to a particularly preferred embodiment, the edible productcontains, per kg of dry matter from onion, at least 2.5 mg of dimethyltrisulfide, 3,4-dimethylthiophene and/or 2-methyl-2-pentenal.

Typically, the edible product contains, per kg of dry matter from onion,not more than 6 mg, more preferably not more than 4 mg of the group Bsubstances.

Per kg of dry matter from onion, the edible product preferably contains0-4 mg, more preferably 0-2 mg of the combination of 5-methylfurfuraland isobutyraldehyde.

The edible product of the present invention is preferably selected fromsoups, sauces, bouillons, savoury concentrates, dressings, seasoningsand snacks. Preferably, the edible product is in the form dry powder(e.g. dry soups, dry sauces or bouillon powders) or in the form of cubesor granulates (e.g. bouillon cubes or bouillon granulates).

Finally, a further aspect of the invention relates to the use of anonion flavour composition for imparting onion flavour to or enhancingonion flavour in an edible product, wherein the onion flavourcomposition is an onion flavour composition as described herein.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES Example 1

An onion flavour composition having an intense sautéed onion flavour wasproduced as follows.

100 g of fresh onions were cut by a slicer to produce onion pieces.

The cut onion pieces were mixed with 87.5 g of onion juice concentrate(80° Bx) to produce an onion mix. The onion mix was dried by vacuum beltdrying for 30 min at 140° C. at a pressure of 8 mbar, to produceapproximately 90 g.

38 g of onion pomace having a dry matter content of appr. 28 wt. % wasdried by hot air drying for 200 min at 130° C. or produce approximately10 g of dried onion pomace.

The dried onion mix and the dried onion pomace were mixed and milled byan impact mill to produce the onion flavour composition.

The onion flavour composition was analysed by means of GC-MS. Table 1shows the result of this analysis (concentration by weight (w/w) of theonion flavour composition).

TABLE 1 Substance mg/kg Dimethyl tetrasulfide 0.44 Dimethyl trisulfide0.94 2-Methyl-2-pentenal 0.59 3,4-Dimethyl-thiophene 2.50 Dipropyldisulfide 0.41 Furfural 0.06 Cis-Methyl-1-propenyldisulfide 0.47Isobutyraldebyde n.d. * 5-methylfurfural n.d. * * n.d. = not detectable

Example 2

An instant onion cream soup having the composition shown in Table 2 wasprepared by dry mixing of the ingredients

TABLE 2 Ingredient Wt. % Instant starch Prejel 70 VA 20 Fat powder SatroFP78 35 Maltodextrin DE 18-20 27.8 Stabilizer Hamulsion ® 2 skimmed milkpowder 2 Onion flavour composition, Example 1 6 Salt 5 MSG 2 Caramelsugar syrup powder 0.2 TOTAL 100

A soup was prepared by stirring 140 g of the instant soup in 1 l waterand boiling for 1 min.

1. A method of producing an onion flavour composition, said methodcomprising: providing onion component selected from fresh onion,dehydrated onion and combinations thereof; providing onion juiceconcentrate having a dry matter content of 40-95 wt. %; mixing the onioncomponent with the onion juice concentrate in a weight ratio, calculatedon a dry matter basis, of 100 parts by weight of dry matter from onioncomponent with 120 to 800 parts by weight of dry matter from onion juiceconcentrate, to produce an onion mix; subjecting the onion mix to a heattreatment at a temperature of 100-200° C. for 10-300 minutes; drying theonion mix to a water content of less than 10 wt. % simultaneous withand/or after the heat treatment; mixing the dried onion mix with theonion pomace in a weight ratio, calculated on a dry matter basis, of 100parts by weight of dry matter from dried onion mix with 4 to 60 parts byweight of dry matter from onion pomace, said onion pomace having a drymatter content of 70-100 wt. %; wherein dry matter of onion constitutesat least 90 wt. % of the dry matter contained in the onion flavourcomposition.
 2. The method according to claim 1, wherein the combinationof onion component and onion juice concentrate constitutes at least 50wt. % of the onion mix.
 3. The method according to claim 1, wherein theonion mix is dried simultaneously with the heat treatment.
 4. The methodaccording to claim 1, wherein the onion mix is dried by means of beltdrying or tray drying.
 5. The method according to claim 1, wherein theonion pomace has a dry matter content of 90-100 wt %.
 6. An onionflavour composition that is obtained by a method according to claim 1,said onion flavour composition comprising: at least 2.5 mg/kg of group Asubstances selected from dimethyl trisulfide, dimethyl tetrasulfide,dipropyl disulfide, 2-methyl-2-pentenal and 3,4-dimethylthiophene andcombinations thereof; 0-4 mg/kg of group B substances selected fromfurfural, isobutyraldehyde, 5-methylfurfural, cis-methyl-1-propenyldisulphide and combinations thereof; wherein the group A substances andthe group B substances are present in the onion flavour composition in amolar ratio of at least 1:1.
 7. The onion flavour composition accordingto claim 6, wherein dry matter from onion constitutes at least 90 wt. %of the dry matter contained in the onion flavour composition.
 8. Theonion flavour composition according to claim 6, wherein the onionflavour composition contains at least 2.5 mg/kg of dimethyl trisulfide,3,4-dimethylthiophene and/or 2-methyl-2-pentenal.
 9. The onion flavourcomposition according to claim 6, wherein the combination of5-methylfurfural and isobutyraldehyde is not contained in the onionflavour composition or present in a combined concentration of not morethan 2 mg/kg.
 10. A process of producing an edible product, said processcomprising combining the onion flavour composition according to claim 6with one or more other edible ingredients.
 11. The process according toclaim 10, wherein the onion flavour composition is applied in an amountthat constitutes at least 0.01 wt. % of the edible product.
 12. Theprocess according to claim 10, wherein the edible product is selectedfrom soups, sauces, bouillons, savoury concentrates, dressings,seasonings and snacks.
 13. Use of an onion flavour composition forimparting onion flavour to or enhancing onion flavour in an edibleproduct, wherein the onion flavour composition is an onion flavourcomposition according to claim
 6. 14. The process according to claim 11,wherein the onion flavour composition is applied in an amount thatconstitutes 0.05-2.0 wt. % of the edible product.